Several hundred thousand patients undergo disc operations each year. Approximately five percent of these patients will suffer recurrent disc herniation, which results from a void or defect which remains in the outer layer (annulus fibrosis) of the disc after surgery involving partial discectomy.
Reference is made to FIG. 1A, an axial cross-section of a normal disc, including the “safe zones.”. The nucleus pulposus 102 is entirely surrounded by the annulus fibrosis 104 in the case of healthy anatomy. Also shown in this cross section is the relative location of the nerves 106. FIG. 1B illustrates the case of the herniated disc, wherein a portion of the nucleus pulposus has ruptured through a defect in the annulus fibrosis, resulting in a pinched nerve 110. This results in pain and further complications, in many cases.
FIG. 1C illustrates the post-operative anatomy following partial discectomy, wherein a space 120 remains adjacent a hole or defect in the annulus fibrosis following removal of the disc material. The hole 122 acts as a pathway for additional material to protrude into the nerve, resulting in the recurrence of the herniation. Since thousands of patients each year require surgery to treat this condition, with substantial implications in terms of the cost of medical treatment and human suffering, any solution to this problem would welcomed by the medical community.
As disclosed and described in the related applications referenced above and incorporated herein by reference, devices used to prevent recurrent disc herniations may be attached in numerous ways, depending upon the extent of the defect, overall patient physiology, and other considerations. For example, such devices may attach to the vertebral endplates, to the annulus fibrosis, to the nucleous pulposus, to the pedicle facet, or other posterior aspect of the vertebrae. Under these more generalized approaches, numerous other more targeted procedures may be used, particularly with respect to annulus fibrosis attachment. For example, devices may be attached to the inner portion of the annulus, including the inner surface, or to the outer surface. With respect to external attachment, positioning typically considers the “safe zone” so as to avoid the great vessels anteriorally, and the nerve or spinal posteriorally.
Given the great variance in defect type, as well as the variability in anatomical structure, particularly at the different vertebral levels, additional methods and apparatus used to maintain devices for preventing recurrent disc herniation are always welcome, particularly if such components, instruments and procedures lend additional stability or longevity.